A Deal With the Devil
by Dinoluvr
Summary: When Percy is feeling hopeless about the war with Gaea, he unintentionally summons something he might come to regret. Forming a contract with Ciel, a small demon boy with a lot of power and an even more powerful butler, become his allies until Gaea is defeated and his soul is Ciel's to keep. Keeping his secret hidden will certainly be a huge challenge, can he do it? Canon pairings.
1. Chapter 1

**_Disclaimer_**_**: **__I do not own Percy Jackson or Kuroshitsuji, if I did then __***Spoiler***__ Percabeth would not have ended up in Tartarus and Ciel would've grown old and married Elizabeth... Just saying. __***End Spoiler***_

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_**Author's Note: **__Alright, so I had this idea when I was sitting in history class today and decided to begin writing it to see what you guys would think about it :) I spent a lot of time planning it, so I'm hoping it comes out relatively decent :D So, anyway, I hope you guys review and let me know what you thought! Everyone who is a reader of my other stories knows that I mention every single reviewer in the Author's Note of my next chapter, so be sure to review if you want a shout out ;) _

_If this receives good feedback, I'll be sure to get out an update this Saturday, so you know when to look for it :)_

**_Spoiler Notices:_**_ This is set after HoH and the second season of Kurshitsuji, aka Black Butler. If you have not finished either of those, I suggest waiting to read this fic. Though, if you don't mind spoilers, by all means continue :3 _

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Percy Jackson sat out on the deck of the _Argo 2 _as he leaned against the rails and looked out over the water_, _contemplating everything that was happening to him and his friends at that moment. Annebeth had gone to sleep an hour or so ago, only after he'd assured her that he was fine; but in all honesty he was far from it. There wasn't a second that went by that he didn't think about their impending battle with Gaea, the crazy earth lady who seemed intent on destroying the world. It was practically driving him crazy as he tried to think of a way that they could possibly beat her.

Despite the optimistic outlook he usually wore, Percy knew it would be impossible for the 7 of them to defeat Gaea's forces; let alone the earth goddess herself. It made him feel… useless, almost. Like, no matter how hard he tried he wasn't going to be able to protect his friends.

"I wish we had some sort of help… Any help." He muttered hopelessly, head in his hands. The god's were pretty much out of commission by this point, so they couldn't rely on them. Not to mention his friends in Camp Half Blood were currently preparing for battle with the Romans, which would be unavoidable if Reyna and Nico didn't get there quickly.

As he was wallowing in his own self-pity, Percy felt a chill run down his spine as if darkness itself was whispering into his ear; and as he looked up he found himself somewhere other than the boat. He was in a dark area, with nothing but sand around him. As he began to panic, a voice began to speak. It was a young voice, no more than twelve or thirteen from what Percy could hear, but he spoke with an authority that could've put adults in their place.

"What is your name?" The voice asked, a black dog with an eye patch of some sort appearing before him.

Despite his predicament, Percy couldn't help but chuckle to himself, "Ahoy matey, does Puppy want a cracker?" He asked with a smirk, his inner voice telling him that he probably shouldn't egg this dog on.

The black dog growled, looking even more menacing if it was possible, "I'm a dog, not a pirate or a bird. I've forgotten how idiotic humans can be." He muttered, seeming to resign himself as he looked at Percy with an apprehensive look. "Now answer my question."

Since it was a bad idea, of course Percy decided to humor this thing for a bit, "Names Jackson, Percy Jackson, and I don't believe I'm the droid you're looking for." He grinned easily, earning an exasperated sigh from the dog. Until now, Percy hadn't realized that the dog was using telepathy to communicate with him.

"Honestly, this guy had to be the one? Not much I can do about it now, I suppose." The dog grumbled, eyes closed as if he was merely talking to himself.

"Uh, dog-thing? I can still hear you… Just saying…" Percy pointed out, raising a finger in the air as if signaling for the creature to notice him.

"Trust me, I know. It'd be impossible to forget you were. Now, what is it you want? You're anguish and hopelessness summoned me to you, after all."

Percy blinked at this statement, wondering how this 'dog' had known all of that. "Summoned you, huh? Well, I guess since you're here I might as well tell you. I want help to defeat Gaea, the earth goddess, and her minions… which just so happen to be giants. I doubt you can do much about that though, this isn't anything like you would've ever seen before. It's probably a million times worse than your worse experience."

The dog gave a wry smile, as if he was almost amused by Percy's statement, "I assure you, you're probably wrong about that. I can help you, but I won't do it for free. If you wish for my help, to save not only the lives of yours friends, but the worlds, then you must give something to me."

The demigod frowned, just knowing there was going to be a gimmick of some kind. Nothing was free in life, after all. "Alright, say I wanted your help. What would I have to give you in return?"

"Oh, nothing much. I simply ask that after our contract expires when Gaea is defeated, you relinquish your soul to me." He answered, tilting his head at Percy as if intrigued to see his response.

"My soul? You mean, like, killing me, or something?" He asked, not fully understanding the meaning behind that statement.

"No. I mean that when our contract expires, I will be allowed to consume your soul." The dog elaborated, the area around them seeming to grow darker as Percy's eyes widened. Consume his soul? Meaning: goodbye Percy? Would he not even be allowed a chance to go to the underworld?

Percy gulped, a bead of sweat sliding down his face as he realized his options. If he said yes and they failed to defeat Gaea, he would die just as if he had said no. Meaning he'd still retain his soul. If he agreed and they did defeat Gaea, Annabeth and the others would be safe to continue their lives.

As he thought that, Annabeth's voice seemed to echo in his mind, _you promised, seaweed brain. _Even if it was only a thought from his nervous mind, it still made his heart hurt. She'd be furious if she ever found out, but he couldn't let her die just so that he would have a chance at the underworld.

Taking a deep breath to steady himself, Percy turned to face the dog as he squared his shoulders. "Alright, I accept your offer. I ask that you tell me your name, however, so I don't have to call you 'dog' all the time."

The creature chuckled, seeming pleased as he began to fade, "My name is Ciel Phantomhive, it was a pleasure doing business with you, Master Percy." He said before fading away completely. As the dog, or rather Ciel, disappeared, so did the dark area he had been in just moments before. A sharp pain erupted on his shoulder on a moment later, and when Percy rolled up his shoulder to inspect it, he was shocked by what he saw.

"That is my mark. It is what binds us together until the finalization of our contract. From this point on, I am your loyal servant." A boy said with a bow, black hair shining with a blue tint as he bowed, a single blue eye glinting in the moon light while the other remained hidden. He was dressed in a t-shirt and shorts, which was so normal that Percy couldn't quite believe this kid had the same voice as the dog from before.

"So… You're the dog?" He asked, voice sounding dumb to his own ears.

Ciel sighed, almost as if to control his frustration before he nodded, "Yes. It seems demons have a sense of humor." He muttered as an afterthought, seeming to remember something as he snapped his fingers. "Sebastian, come here."

"Yes, my young Master?" A rather tall man with dark hair and auburn colored eyes inquired, a kind smile on his face as he appeared behind Ciel.

"Master Percy," He began, sounding as if he stumbled a bit on the 'Master' part, "this is my butler, Sebastian." He explained, and Percy could only assume that this man was what Ciel just happened to be. A demon; or so he understood.

Sebastian bowed to Percy as well, looking out of place in his own set of modern clothing including a t-shirt and jeans. The demigod pursed his lips as he looked at the strange pair, wondering how he was going to explain this to the group.

As he mind worked overtime, Percy began to tell them their 'story', so to speak. "Alright, so you guys were stranded in the ocean and I decided to save you. Upon saving you, I found out you were demigod's who had been marooned after your ship was destroyed. You are both children of… Aphrodite, which explains your good looks. Oh, and you're brothers… I mean, you look similar enough." He rambled, and the two demons shared a silent look as he explained this theory.

"I'm just hoping Annabeth and Piper can't tell that I'm lying, because then my girlfriend would kill me upon finding out _why _I had lied. So please, just lie low and don't act suspicious. None of this master stuff. Simply call me Percy, and I'll call you guys by your names, ok?" he said with a grin, as if his whole idea was perfectly ingenious.

Not looking impressed in the least, Ciel simply nodded, "As you wish, Percy." He replied before glancing around the ship. "Where are your quarters located so that I know where I can find you if need be? Also, where will Sebastian and I be staying?"

The next half-hour was then spent as Percy explained different areas of the ship before leading them to the only open room, apologizing but trying to make it sound as if it would help his plan. "It just helps solidify the fact that you guys are brothers, right?" he asked, trying to earn even an enthusiastic smile from one of them.

Ciel sighed, "It's fine. If you need something, simply summon me."

Percy nodded and left the room after saying a quick 'see ya', examining the mark on his right shoulder as he walked to his room. It was bright blue in color, with what looked like swirling designs within it. He supposed he could pass it off as a tattoo, but it'd be hard to explain how he got it.

_When? Well, you see, back when we were in Tartarus and you were asleep, there was this little tattoo parlor across from the temple where I decided to get a tattoo so that I would always remember my time there. Awesome, huh?_

Yeah right, with that explanation he could just see himself getting judo kicked into the wall. Sighing as he ran a hand through his hair, he just figured he'd have to hope that it just stayed hidden long enough for him to come up with a good explanation. Even better would be if Annabeth didn't really care about the mark and didn't care about where it came from, which would never happen unless pig's began to fly.

This was going to be fun. Not.


	2. Chapter 2

_**Author's Note: **__Here you are everyone, chapter 2! :3 I wish to thank every who faved, followed, and reviewed since I know it probably wasn't easy to discover this incredibly strange Fanfic X3 Anywho, I wish to just do a few shoutouts to everyone who reviewed on the last chapter real quick:_

_Paxloria_

_koryandrs_

_Woww_

_animebookfangrl_

_black blood of the red rose_

_Also, I would like to respond to a guest comment real quick, feel free to skip this if it wasn't you :) They inquired about a PercyxCiel or SebaxCiel pairing, and I would like to let them know what I thought :D I don't mind yoai/slash, some are even my favorite pairings, but I unfortunately like Percabeth more than almost any other pairing :/ I'm sorry DX As for SebaxCiel, I will probably not include it, though I'll probably make a few innuendos just as the anime did X3 Again, I always preferred Ciel with Aloise or Elizabeth :/ I'll do some fanservice in later chapters for you though, don't worry! :D (Also, I couldn't do that to poor Nico ;( He did call dibs, after all X3)_

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The next morning, Percy awoke with a yawn and stretched as he smiled at the new day. That is, until he remembered what he had done last night. Smacking his forehead as he groaned and fell back on the pillow, Percy repeatedly cursed himself for his stupid decision. Could you get a refund on soul exchanges? No? Dam his stupid brain. Heh. Dam.

Forcing himself to focus, Percy quickly got dressed as he made sure to cover his mark, hoping that the demons were still asleep or something so that he could explain to everyone before they came up. Rushing to the upper deck, his heart sunk as he saw each of the _Argo 2 _members surrounding the two, intrigued by them.

Ciel looked up as Percy came above deck, and smiled to him, "Ah, Percy, there you are. I was just explaining to your crew mates how you saved my father and I from drowning after our fishing boat got swept out to sea. You see, we're originally from Britain, and we had gone on vacation when this storm came along and pushed us off course." He explained, turning back to the group with an innocent smile.

Percy blinked in surprise, knowing for a fact that wasn't the story he had told them. On a side note, he noticed for the first time that they did, in fact, have pretty distinct British accents. Huh.

Fortunately, everyone seemed to accept Ciel's story as they nodded along with him, and Percy began to wonder if he really was a child of Aphrodite and had some form of charm speak. Or maybe it was just some demon power of his.

"Oh, right. Yeah. It was nothing." He said with an indifferent shrug, coming over to stand by Annabeth as he wrapped an arm around her waist.

Annabeth briefly smiled up at him, only a tiny glimmer of uncertainty in her eyes before she turned back to the pair, obviously trying to see how believable their story was. "You guys are just simple fisherman than? No… Strange abilities or whatnot?" She asked, and Jason nodded his agreement on the question.

Ciel glanced up at Sebastian, pretending to ask a silent question, before turning back to the group. "We can see threw the mist. I can because I'm a demigod, my father just has the gift. My mother was Aphrodite." He explained, finally using some of Percy's story. The demigod was silently pleased that the gods were at war with themselves now, since it meant they couldn't deny his story.

Annabeth nodded, completely buying it somehow, "That's good. This journey is still too dangerous for you though, we'll drop you off next time we see land." She told them, as if trying to give comfort.

Ciel shook his head with a slight smirk, "There's no need to worry about us. We can hold our own." He assured her, meeting her eyes as the barest flash of red crossed them.

Annabeth nodded once more, "Alright, you'll stay with us then." She said without even an argument, and Percy looked between her and Ciel with a look of disbelief. How did he do that?! He'd have to tell the demon to teach him, sometime.

Ciel's hair seemed much bluer in color now, which was kind of odd, but he decided not to say anything about it. The other's seemed less reluctant to allow them to stay. "Are you sure that's a good idea, Annabeth?" Piper asked, obviously suspecting charm speak now that she thought Ciel was her half-brother.

She nodded in response, "Yes, I'm sure."

Leo shrugged and went to go mess with his controls again, "Alright, welcome aboard!" he said with a grin, checking to make sure they were on course to Athens as he spoke.

Jason nodded as well, taking Piper's hand as if to assure her that it was fine, "Yes, welcome. I hope you guys realize what you're getting yourselves into…"

Hazel and Frank welcomed the two as well, though Hazel's only concern was why the son spoke more than the father, and she voiced this to her boyfriend when they were out of earshot. Frank simply shrugged, not thinking much of it, "Maybe his dad's just a quiet guy. I'd let my son talk to a bunch of strange people if that's what he wanted, who cares how old he is?" Despite not being convinced, Hazel agreed reluctantly before heading off to help Piper practice her swordplay, knowing she could talk to her about the visitors as well. It was too convenient in her opinion.

Percy sat against the railing as Annabeth joined him, looking over the waves as her boyfriend watched the two newcomers as they talked quietly amongst themselves. He expected her to punch him and throw him over board any second now, prepared for her to discover his secret within a few moments.

"Why are you so nervous, seaweed-brain?" She asked him with an amused smile as she turned to look at him, raising an eyebrow.

Percy smiled at her, trying to seem as nonchalant as possible, "It's nothing. I'm just worried about Gaea." He lied, a whole new list of worries at the front of his mind.

Annabeth rolled her eyes, wrapping her arms around him as if to comfort him. "Don't worry. We'll be alright… I hope." She sighed, and Percy absentmindedly rubbed her back.

"You're right, we'll be fine." He agreed, if the demons actually held up their end of the bargain, that is.

"Percy!" a shout came from the side of the ship where Jason was, watching for anything that could potentially kill them. Which seemed to be just about anything these days. Percy frowned as Annabeth moved away, and they both instantly responded by running up. Percy looked into the water and his eyes widened as he was met with a giant shadow underneath the water, a glimpse of it coming above water before disappearing again.

He and Annabeth looked at each other as they both got a sinking feeling in the pit of their stomach, automatically knowing what was down there. "I'll be back." He told them before leaping onto the railing, the only thing stopping him from jumping into the water was Annabeth as she grabbed his arm. "Perseus Jackson, I swear to the gods that if you jump down there…" she began, but he silenced her with a quick kiss.

"Don't worry so much, I'll be back for you, wise-girl." He assured her with a grin before plummeting into the water. He noticed Ciel and Sebastian standing at the railing as well, watching him with an exasperated look.

Percy turned around to find the source of the shadow swimming down a ways to find it. A few yards below the ship, the demigod searched the water until he felt a presence behind him and turned around, coming face to face with the eye of a giant squid. A squid even bigger than the once they had faced back when they were searching for the Fleece.

Crap. It was the Kraken. The Kraken was going to try to eat them. Crap. Crap. Crap.

As he looked at the creature, it turned the angle it was swimming at so that it was heading for the boat, intending to ram it. Percy gasped and used all his might to push him off target with the water surrounding them, successfully pushing it so that it came out of the water next to the boat, causing the boat to surge away as it crashed back down.

Percy grimaced as he pushed himself out of the water, managing to land on board the ship before he quickly got up and noticed that everyone was running to get into position. Frank had disappeared, until Percy saw an eagle soaring over head the randomly turned into a shark before dropping into the water.

Annabeth cursed as she saw the same thing, turning to Percy with panic in her eyes, "Get Frank back on board, now! We need Jason to zap the water and we can't do that with him in there!" She ordered, and Percy nodded immediately.

Jason had already moved to the top point of the ship where Nico used to stay, and was already pulling out his sword as he prepared to strike the squid with lightning. Hazel was busy trying to shoot the squid in the eyes with arrows as Frank drew it's attention from the ship, and Piper was charm speaking as she threw food at it.

Appreciating their efforts, Percy ran to the side of the ship where Frank was battling the squid, focusing his energy's as he had the water surge upward, bringing the shark with him. _Frank, turn into a bird or something and get on this ship. _He thought, hoping he was close enough for the demigod to hear him.

Apparently he did, because the next minute he had turned into an eagle again before landing on the ship and turning human. "Good job, Frank, you gave Jason enough time to power up." Percy told him as he clapped him on the shoulder, gesturing to Jason.

Lighting began to build in the sky as they all watched, and the next instant it crashed down, striking the squid as it made a shrieking noise of pain within Percy's mind, causing him to wince. The creature floated on the surface afterword, not even a tentacle moving.

Everyone sighed in relief, except for Ciel and Sebastian who had somehow found tea somewhere on the ship, and were drinking it quietly. "Are you just about done screaming now? I swear, all this fuss over a squid." He remarked, glancing up at them as he set down his fancy little tea cup.

Everyone gaped at them, including Percy, whose disbelief quickly changed to chagrin, "You mean to tell me you didn't help _at all? _What about our agreement?" he demanded, practically growling at the two of them.

"You didn't order us to help. Not to mention it seemed like you guys had it plenty under control." He answered with a small smirk, knowing he was right.

Percy glared at the boy when a hand was put on his shoulder, gripping it tightly, "Percy… What do you mean _agreement?" _Annabeth inquired with her voice full of contained anger as she looked at him.

_Dam demons. _

"Well, you see, what I meant was…" He began, searching for the words that would let him off the hook.


	3. Chapter 3

_**Author's Note: **__An easy little chapter I wrote while watching TV, so I hope it turned out ok X3 My brain is fried from Nanowrimo, so I had no real ideas for anything today, but I didn't want to let you guys down... So feel special ;)_

_xXLoverOrHaterXx_

_Paxloria_

_koryandrs_

_Mushroom3565_

_Thank you all for reviewing! :D_

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"What I meant was… We had an agreement where… They would… Help us in any way they could if we were to be, say, attacked by something… I mean, Ciel here is a demigod after all, he knows how to fight and all that…" He stammered, the demons sharing a glance as Ciel tried not to facepalm at his masters awful attempt to save himself.

"What Percy is trying to say is that in order to come along with you guys, we had to make ourselves useful and do whatever he told us." He lied easily, handing his teacup to the man at his side. His eyes flashed red once more as he glanced up at Annabeth, and it took only a moment for her to calm down and accept what had been said.

"Right… Makes sense." She nodded, smiling at them before heading off to help clean up the damage to the ship.

Percy frowned after her before whirling on the small boy, giving him a sort of glare. "Both of you, my room, now." He ordered quietly, fully intending to chide the boy on disobeying his orders at every turn. What happened to being his loyal servant? You'd think he'd be at least a little loyal since he first showed up as a dog. How ironic.

Marching the exasperated demon boy into his room with the tall, stoic man following behind him, Percy spoke, "Alright, _Ciel_, what happened to our story? Why didn't you help? I just sold you my _soul, _and all you've done so far is hypnotize my girlfriend with your demonic powers, which I'm really starting to hate. Sure, I don't want to get stabbed, but I don't want anyone messing with her mind either."

Ciel listened quietly to Percy's rant, only looking up at him once he had finished, "You're idea was idiotic, you're girlfriend would never have fallen for it. She barely fell for our _enhanced _version, my powers were the only reason she did. She's brilliant, I don't know if you've noticed that or not, so she isn't going to be fooled easily. Secondly, I follow direct orders. You never told me to help, and it didn't appear to me that you're life was in danger. I think I told you that earlier. If you wish me to stop influencing Annabeth, you merely have to order me to do so." He shot back defiantly, chest puffed out as he looked Percy square in the eyes.

He had to give the kid credit; he was pretty tough for someone his age. Percy ran a hand through his hair, "Fine. No more hypnotizing Annabeth, or using any other powers on her for that matter. Also, if we're attacked, I want your first priority to be keeping Annabeth safe. Next, stick to _my _stories or discuss a change with me before hand. We clear?"

Ciel pursed his lips, looking apprehensive as he nodded, "…Crystal."

Percy grinned with relief, "Sweet. Now, if you'll excuse me, I have to go find my girlfriend. Why don't you guys… Prepare us a picnic? Perhaps at the back, so we can eat and then watch the sunset." He thought allowed, rubbing his chin as he considered his 'perfect' date. "Yeah, sounds good."

Ciel resisted the urge to roll his eyes and gave a shallow bow, "Of course, Percy."

Percy nodded, "Great, make it look good." He said before waving and heading out, hearing the demons murmuring to each other once he had left. When he got back onto deck, he found Annabeth discussing something with Leo as he walked over, and found that it was something about directions and sailing and whatnot.

Annabeth smiled as he walked up, "There you are, Sea-weed Brain. Have you seen Ciel and Sebastian around anywhere?"

Percy pretended to think about it before shaking his head, looking at her apologetically as he wrapped a hand lightly around her waist. "Nope. How's our course for Gaea?" he asked, quickly changing the subject as he glanced between them.

Leo grinned, "No worries, man. We're back on track, ol' squid face couldn't mess us up that bad." He assured him with a grin, and Percy grinned back.

"Sweet, dude. Keep up the good work." He said, clapping the boy on the shoulder as he saw Ciel and Sebastian come above deck, the demon boy giving him a pointed look.

With a nod of gratitude, Percy instantly nudged Annabeth as he turned to face her with a raised eyebrow, "You hungry?" he asked with a grin.

Annabeth blinked up at him, "Uh, sure. Why?"

"I'm starving!" Leo piped up, raising his hand as Percy rolled his eyes at him.

"Sorry, man, girlfriends only." He chuckled, messing up his hair as he walked past with Annabeth at his side.

"That's cold!" Leo laughed, waving them off as he returned to his controls.

Percy led Annabeth to the back of the ship, coming upon a blanket covered in various dishes so that they could face the ocean as the sun sat at the horizon.

Annabeth gaped at the scene, shaking her head as if to see if it was real, "Wha… What's this?" She stammered, trying to keep her composure.

Percy shrugged, "Seeing as our last date was in the pit of Tartarus in an old Hades temple, I figured I would go for something a little more romantic this time." He chuckled, leading her to the blanket.

She continued to gape between him and the food before a small grin formed across her face. "Percy… This… This is incredible… Thank you." She whispered, looking up at him.

Percy shrugged it off, handing her a strawberry that was sitting on one of the plates. "No worries, only the best for the best girlfriend around." He grinned, giving her a kiss.

Annabeth giggled, blushing slightly as she punched his shoulder, "Sea-weed Brain." She mumbled, smiling as she ate the strawberry.

Glancing behind him, he saw Ciel and Sebastian standing off in the shadows, and he nodded to them once more. "Thank you." He mouthed silently before turning back to the sea, leaning his head against Annabeth as she rested her on his shoulders.


End file.
